kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 205 insertions, 0 deletions

diff --git a/include/rdma/iw_cm.h b/include/rdma/iw_cm.h
new file mode 100644
index 000000000..57b33edd9
--- /dev/null
+++ b/include/rdma/iw_cm.h
@@ -0,0 +1,205 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/*
+ * Copyright (c) 2005 Network Appliance, Inc. All rights reserved.
+ * Copyright (c) 2005 Open Grid Computing, Inc. All rights reserved.
+ */
+
+#ifndef IW_CM_H
+#define IW_CM_H
+
+#include <linux/in.h>
+#include <rdma/ib_cm.h>
+
+struct iw_cm_id;
+
+enum iw_cm_event_type {
+	IW_CM_EVENT_CONNECT_REQUEST = 1, /* connect request received */
+	IW_CM_EVENT_CONNECT_REPLY,	 /* reply from active connect request */
+	IW_CM_EVENT_ESTABLISHED,	 /* passive side accept successful */
+	IW_CM_EVENT_DISCONNECT,		 /* orderly shutdown */
+	IW_CM_EVENT_CLOSE		 /* close complete */
+};
+
+struct iw_cm_event {
+	enum iw_cm_event_type event;
+	int			 status;
+	struct sockaddr_storage local_addr;
+	struct sockaddr_storage remote_addr;
+	void *private_data;
+	void *provider_data;
+	u8 private_data_len;
+	u8 ord;
+	u8 ird;
+};
+
+/**
+ * typedef iw_cm_handler - Function to be called by the IW CM when delivering
+ * events to the client.
+ *
+ * @cm_id: The IW CM identifier associated with the event.
+ * @event: Pointer to the event structure.
+ */
+typedef int (*iw_cm_handler)(struct iw_cm_id *cm_id,
+			     struct iw_cm_event *event);
+
+/**
+ * typedef iw_event_handler - Function called by the provider when delivering
+ * provider events to the IW CM.  Returns either 0 indicating the event was
+ * processed or -errno if the event could not be processed.
+ *
+ * @cm_id: The IW CM identifier associated with the event.
+ * @event: Pointer to the event structure.
+ */
+typedef int (*iw_event_handler)(struct iw_cm_id *cm_id,
+				 struct iw_cm_event *event);
+
+struct iw_cm_id {
+	iw_cm_handler		cm_handler;      /* client callback function */
+	void		        *context;	 /* client cb context */
+	struct ib_device	*device;
+	struct sockaddr_storage local_addr;      /* local addr */
+	struct sockaddr_storage	remote_addr;
+	struct sockaddr_storage m_local_addr;	 /* nmapped local addr */
+	struct sockaddr_storage	m_remote_addr;	 /* nmapped rem addr */
+	void			*provider_data;	 /* provider private data */
+	iw_event_handler        event_handler;   /* cb for provider
+						    events */
+	/* Used by provider to add and remove refs on IW cm_id */
+	void (*add_ref)(struct iw_cm_id *);
+	void (*rem_ref)(struct iw_cm_id *);
+	u8  tos;
+	bool tos_set:1;
+	bool mapped:1;
+	bool afonly:1;
+};
+
+struct iw_cm_conn_param {
+	const void *private_data;
+	u16 private_data_len;
+	u32 ord;
+	u32 ird;
+	u32 qpn;
+};
+
+enum iw_flags {
+
+	/*
+	 * This flag allows the iwcm and iwpmd to still advertise
+	 * mappings but the real and mapped port numbers are the
+	 * same.  Further, iwpmd will not bind any user socket to
+	 * reserve the port.  This is required for soft iwarp
+	 * to play in the port mapped iwarp space.
+	 */
+	IW_F_NO_PORT_MAP = (1 << 0),
+};
+
+/**
+ * iw_create_cm_id - Create an IW CM identifier.
+ *
+ * @device: The IB device on which to create the IW CM identier.
+ * @cm_handler: User callback invoked to report events associated with the
+ *   returned IW CM identifier.
+ * @context: User specified context associated with the id.
+ */
+struct iw_cm_id *iw_create_cm_id(struct ib_device *device,
+				 iw_cm_handler cm_handler, void *context);
+
+/**
+ * iw_destroy_cm_id - Destroy an IW CM identifier.
+ *
+ * @cm_id: The previously created IW CM identifier to destroy.
+ *
+ * The client can assume that no events will be delivered for the CM ID after
+ * this function returns.
+ */
+void iw_destroy_cm_id(struct iw_cm_id *cm_id);
+
+/**
+ * iw_cm_listen - Listen for incoming connection requests on the
+ * specified IW CM id.
+ *
+ * @cm_id: The IW CM identifier.
+ * @backlog: The maximum number of outstanding un-accepted inbound listen
+ *   requests to queue.
+ *
+ * The source address and port number are specified in the IW CM identifier
+ * structure.
+ */
+int iw_cm_listen(struct iw_cm_id *cm_id, int backlog);
+
+/**
+ * iw_cm_accept - Called to accept an incoming connect request.
+ *
+ * @cm_id: The IW CM identifier associated with the connection request.
+ * @iw_param: Pointer to a structure containing connection establishment
+ *   parameters.
+ *
+ * The specified cm_id will have been provided in the event data for a
+ * CONNECT_REQUEST event. Subsequent events related to this connection will be
+ * delivered to the specified IW CM identifier prior and may occur prior to
+ * the return of this function. If this function returns a non-zero value, the
+ * client can assume that no events will be delivered to the specified IW CM
+ * identifier.
+ */
+int iw_cm_accept(struct iw_cm_id *cm_id, struct iw_cm_conn_param *iw_param);
+
+/**
+ * iw_cm_reject - Reject an incoming connection request.
+ *
+ * @cm_id: Connection identifier associated with the request.
+ * @private_data: Pointer to data to deliver to the remote peer as part of the
+ *   reject message.
+ * @private_data_len: The number of bytes in the private_data parameter.
+ *
+ * The client can assume that no events will be delivered to the specified IW
+ * CM identifier following the return of this function. The private_data
+ * buffer is available for reuse when this function returns.
+ */
+int iw_cm_reject(struct iw_cm_id *cm_id, const void *private_data,
+		 u8 private_data_len);
+
+/**
+ * iw_cm_connect - Called to request a connection to a remote peer.
+ *
+ * @cm_id: The IW CM identifier for the connection.
+ * @iw_param: Pointer to a structure containing connection  establishment
+ *   parameters.
+ *
+ * Events may be delivered to the specified IW CM identifier prior to the
+ * return of this function. If this function returns a non-zero value, the
+ * client can assume that no events will be delivered to the specified IW CM
+ * identifier.
+ */
+int iw_cm_connect(struct iw_cm_id *cm_id, struct iw_cm_conn_param *iw_param);
+
+/**
+ * iw_cm_disconnect - Close the specified connection.
+ *
+ * @cm_id: The IW CM identifier to close.
+ * @abrupt: If 0, the connection will be closed gracefully, otherwise, the
+ *   connection will be reset.
+ *
+ * The IW CM identifier is still active until the IW_CM_EVENT_CLOSE event is
+ * delivered.
+ */
+int iw_cm_disconnect(struct iw_cm_id *cm_id, int abrupt);
+
+/**
+ * iw_cm_init_qp_attr - Called to initialize the attributes of the QP
+ * associated with a IW CM identifier.
+ *
+ * @cm_id: The IW CM identifier associated with the QP
+ * @qp_attr: Pointer to the QP attributes structure.
+ * @qp_attr_mask: Pointer to a bit vector specifying which QP attributes are
+ *   valid.
+ */
+int iw_cm_init_qp_attr(struct iw_cm_id *cm_id, struct ib_qp_attr *qp_attr,
+		       int *qp_attr_mask);
+
+/**
+ * iwcm_reject_msg - return a pointer to a reject message string.
+ * @reason: Value returned in the REJECT event status field.
+ */
+const char *__attribute_const__ iwcm_reject_msg(int reason);
+
+#endif /* IW_CM_H */